Liquid crystal display apparatus, manufacturing method thereof, and liquid crystal projector

ABSTRACT

A highly moisture-resistant liquid crystal display apparatus which is capable of suppressing display deterioration due to occurrence of image retention without impairing properties including gap controllability and alignment stability maintenance, and a manufacturing method thereof, are provided. The liquid crystal display apparatus includes: a first sealing member  15  arranged at an outer periphery of a liquid crystal layer  17  sandwiched between a pair of substrates  11  and  12;  and a second sealing member  16  arranged at an outer periphery of the first sealing member  15  in contact with the pair of substrates  11  and  12.  The second sealing member  16  is formed from an alkylsiloxane compound as a main ingredient which is formed into an inorganic film by irradiation with an ultraviolet radiation. The alkylsiloxane compound is a di-alkylsiloxane compound or di-methyl-siloxane compound.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display apparatus, amanufacturing method thereof, and a liquid crystal projector using theliquid crystal display apparatus.

2. Description of the Related Art

In recent years, projection type image display apparatuses of the typeusing a reflection type liquid crystal display called “LCOS (LiquidCrystal on Silicon) display” in the art of liquid crystal displays havebeen widespread. Such a projection type image display apparatus iscapable of displaying images that are smoother and havehigher-definition and higher color reproducibility than projection typeimage display apparatuses of the type using a transmission type liquidcrystal display.

Such liquid crystal displays as reflection type liquid crystal displaysof the LCOS type, in general, have a structure in which a liquid crystalmember is held by peripheral sealing formed at a peripheral portion ofthe display and end sealing. A resin sealing adhesive is typically usedfor both the peripheral sealing and the end sealing.

Such a resin sealing adhesive calls for an essentially required propertyof preventing the liquid crystal member from leaking out of the liquidcrystal display, as well as many other properties. Specifically, suchproperties include a property of failing to affect a control of the gapbetween opposing substrates, a property of maintaining electro-opticcharacteristics of the liquid crystal display under a high-temperatureand high-humidity environment, and a property of stabilizing a liquidcrystal alignment. Actually, however, a common resin sealing adhesiveused in the liquid crystal display manufacturing stage cannot completelyprevent penetration of moisture under the high-temperature andhigh-humidity environment. Therefore, liquid crystal displays involve aproblem with maintenance of the electro-optic characteristics under thehigh-temperature and high-humidity environment.

A reflection type liquid crystal display of the LCOS type, inparticular, has a transparent ITO electrode and a metal pixel electrodeas opposing electrodes and, hence, the work functions of the twoelectrode materials are not equal to each other. Such an electrodeconfiguration is called an variety electrode configuration. With thevariety electrode configuration, it is conventionally known thatpositive ions and negative ions contained in the liquid crystal memberare likely to come out of balance when a very small amount of moistureis mixed into the liquid crystal member.

Such imbalance of ions in the liquid crystal member leads to imageretention. For this reason, preventing penetration of moisture is animportant challenge for such a reflection type liquid crystal display ofthe LCOS type in order to prevent the image retention also.

Many techniques have been proposed to solve to the problem of moisturepenetration into a liquid crystal display. For example, Japanese PatentApplication Laid-Open No. S60-026321 has proposed a technique of forminga resin structure at a peripheral portion of a liquid crystal display.

Specifically, the technique described therein includes providing adouble-structure sealing portion in which a low water permeability resin(for example an epoxy adhesive) is used for a first sealing in contactwith a liquid crystal layer while a resin having a strong adhesion to aflexible substrate (for example a silicone adhesive) is used for anouter second sealing. Alternatively, the technique described thereinincludes providing a double-structure sealing portion in which a resinthat is difficult to react with a liquid crystal (for example a siliconeadhesive) is used for the first sealing in contact with the liquidcrystal layer, while a low water permeability resin (for example anepoxy adhesive) is used for the outer second sealing.

Japanese Patent Application Laid-Open No. S62-058221 has proposed atechnique of depositing a metal oxide formed from an organic metalcompound as a raw material over a moisture penetration passage in orderto improve the moisture resistance of a display apparatus under thehigh-temperature and high-humidity environment by leaps and bounds.

SUMMARY OF THE INVENTION

In cases where the technique described in Japanese Patent ApplicationLaid-Open No. S60-026321 is used, the water permeability of the resinstructure cannot ensure a sufficient moisture resistance. Therefore, thetechnique does not reach an essential solution, though bringing about alife prolonging effect under the high-temperature and high-humidityenvironment. When an attempt is made to obtain a sufficient moistureresistance by the provision of the resin structure, a portion of theresin structure which is formed at the peripheral portion of the liquidcrystal display becomes thick and bulky, thus resulting in the entireliquid crystal display having a large structure. Such an arrangement isconsiderably disadvantageous to projection type image displayapparatuses calling for downsizing in particular.

There is also an attempt to improve the moisture resistance remarkablyby utilizing a dense thin film of silicon oxide or silicon nitride whichfunctions as a moisture-resistant film having a high moisture barrierproperty, as in Japanese Patent Application Laid-Open No. S62-058221.However, during the process of converting the organic metal compounddeposited on the liquid crystal display to an inorganic substance byeliminating an organic functional group from the organic metal compound,a resin sealing adhesive used for the peripheral sealing and the endsealing is subjected to a temperature higher than glass transitiontemperature thereof.

Such an elevated temperature causes the resin sealing adhesive to melt,thus varying the dimensions of the resin sealing adhesive. For thisreason, neither a desired cell gap nor a sufficient sealing effectagainst the liquid crystal member can be obtained. Further, the resinforming the adhesive may be thermally decomposed to produce impurities,which increase the likelihood of display deterioration due to imageretention.

The projection type image display apparatuses, particularly theprojection type image display apparatuses of the type using a reflectiontype liquid crystal display cannot obtain a good display quality becausean uneven cell gap of the liquid crystal display is emphasized by amagnifying projection system. Also, the display quality deteriorationdue to image retention caused by impurity ions is a more serious problemwith the projection type image display apparatuses which apply intensivelight to the respective liquid crystal displays over a prolonged timethan with direct-view type liquid crystal display apparatuses.

An object of the present invention is to provide a highlymoisture-resistant liquid crystal display apparatus which is capable ofsuppressing display deterioration due to occurrence of image retentionwithout impairing properties including gap controllability and alignmentstability maintenance, as well as a manufacturing method thereof.Another object of the present invention is to provide a liquid crystalprojector which is capable of realizing good display quality and highreliability.

A liquid crystal display apparatus according to the present inventionincludes: a first sealing member arranged at an outer periphery of aliquid crystal layer sandwiched between a pair of substrates; and asecond sealing member arranged at an outer periphery of the firstsealing member in contact with the pair of substrates, wherein thesecond sealing member is formed from an alkylsiloxane compound as a mainingredient which is formed into an inorganic film by irradiation with anultraviolet radiation.

A method of manufacturing a liquid crystal display apparatus accordingto the present invention includes: a first step of injecting a liquidcrystal into a space defined by a pair of substrates and a first sealingmember bonding together the pair of substrates to form a firststructure; and a second step of forming an alkylsiloxane compound at anouter periphery of the first sealing member in contact with the pair ofsubstrates, and irradiating the alkylsiloxane compound with anultraviolet radiation to form a second structure having an inorganicfilm.

According to the present invention, a highly moisture-resistant liquidcrystal display apparatus can be provided which is capable ofsuppressing display deterioration due to occurrence of image retentionwithout impairing properties required of a resin sealing adhesive,including gap controllability and alignment stability maintenance.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view illustrating one exemplaryembodiment of a reflection type liquid crystal display apparatusaccording to the present invention.

FIG. 2 is a schematic plan view of the reflection type liquid crystaldisplay apparatus illustrated in FIG. 1.

FIG. 3 is a schematic view illustrating one exemplary embodiment of aliquid crystal projector according to the present invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments for carrying out the presentinvention will be described in detail with reference to the drawings.FIG. 1 is a schematic sectional view illustrating a reflection typeliquid crystal display apparatus of the LCOS type according to thepresent invention, and FIG. 2 is a schematic plan view of the reflectiontype liquid crystal display apparatus.

The liquid crystal display apparatus shown includes: a translucentsubstrate 11 including a glass substrate having a transparent electrode;and a single crystal semiconductor substrate (single crystal siliconsubstrate or the like) 12 having an effective pixel region in whichpixels each having a switching element and a reflective electrode arearranged in a two-dimensional array. The effective pixel region extendsinwardly of a first sealing member 15. The translucent substrate 11 andthe single crystal semiconductor substrate 12 are a pair of substratessandwiching a liquid crystal layer 17 therebetween.

The liquid crystal display apparatus also includes a transparentelectrode 13, a reflective pixel electrode 18, and alignment films(i.e., alignment control films) 14 a and 14 b. The pair of substratesincluding the translucent substrate 11 and the single crystalsemiconductor substrate 12 have, at opposing surfaces thereof, thealignment films respectively. The alignment films 14 a and 14 b are eachan oblique vapor deposition film formed by oblique vapor deposition ofan inorganic material such as silicon oxide, or a like film.

A resin sealing layer (i.e., peripheral sealing) 15 is the first sealingmember, and an inorganic film 16, which is the second sealing memberarranged at an outer periphery of the first sealing member 15, is formedfrom an alkylsiloxane compound as a main ingredient. As illustrated inFIG. 1, the first sealing member 15 is arranged at an outer periphery ofthe liquid crystal layer 17 sandwiched between the pair of substrates.

The second sealing member 16 is arranged at an outer periphery of thefirst sealing member 15. The second sealing member 16 is formed from analkylsiloxane compound as a main ingredient which is formed into aninorganic film by irradiation with an ultraviolet radiation.

This inorganic film is arranged in contact with at least one of thetranslucent substrate 11 and the single crystal semiconductor substrate12 or with at least one of the alignment films 14 a and 14 b formed overthe opposing surfaces, respectively, of the pair of substrates 11 and12. (The inorganic film is arranged in contact with at least one of thetranslucent substrate 11 and the alignment film 14 a and with at leastone of the single crystal semiconductor substrate 12 and the alignmentfilm 14 b.) The organic film can be arranged in contact with thealignment films 14 a and 14 b both.

A sealing member 19 illustrated in FIG. 2 is a member for sealing aninjection region opened at the first sealing member 15 for injection ofthe liquid crystal layer 17. A dummy electrode 20 is illustrated in FIG.1.

Examples of alkylsiloxane compounds include silicone materials such as adi-alkylsiloxane compound and a di-methyl-siloxane compound.Specifically, such an alkylsiloxane compound is a compound at a state ofan alkylsiloxane structure at a temperature equal to or lower than glasstransition temperature of the first sealing member 15 (for example,di-methyl-silicone oil or di-methyl-silicone gas). As described above,the alkylsiloxane compound is formed into silicon oxide by irradiationwith an ultraviolet irradiation.

In cases where silicon oxide is used for the alignment films, thealignment films and the second sealing member 16 are formed from thesame material and, hence, the adhesion therebetween is enhanced toenable the moisture resistance of the liquid crystal display apparatusto be further improved. Because the oblique vapor deposition film, inparticular, is formed so as to fill up gaps between needle-likestructures of silicon oxide, the adhesion is particularly enhanced toenable the moisture resistance to be further improved. Thus, the obliquevapor deposition film is desirable. In this case, the alignment filmformed over at least one of the pair of substrates 11 and 12 can bearranged in contact with the inorganic film, and the alignment film andthe inorganic film can be formed from the same material.

As the translucent substrate 11, a substrate which transmits visiblerays of light therethrough, such as a glass substrate or a quartzsubstrate for use in a liquid crystal device, is used. The surface ofthe translucent substrate 11 which opposes the single crystalsemiconductor substrate 12 is formed with the transparent electrode 13formed from a transparent conductive material such as SnO₂ or ITO(indium tin oxide).

The transparent electrode 13 formed at the translucent substrate 11 maybe configured to prevent reflection at the interface with the liquidcrystal member by being combined with a silicon oxide thin film, analuminum oxide thin film or the like. Alternatively, a reflectionpreventive film including a multilayered inorganic dielectric film orthe like may be formed over a surface of the translucent substrate 11which is opposite away from the surface formed with the transparentelectrode 13.

The single crystal semiconductor substrate 12 is formed with thereflective pixel electrode (i.e., pixel electrode having a lightreflective property) 18. The reflective surface of the reflective pixelelectrode 18 is formed from aluminum, silver or an alloy thereof. Thoughaluminum is used for the reflective surface, there is no particularlimitation on the material used for the reflective layer. Thethicknesses of both the translucent substrate 11 and the single crystalsemiconductor substrate 12 are not particularly limited.

The alignment films 14 a and 14 b are formed at the interface betweenthe translucent substrate 11 and the liquid crystal member 17 and theinterface between the single crystal semiconductor substrate 12 and theliquid crystal member 17, respectively. One of an oblique vapordeposition film of an inorganic dielectric material, such as siliconoxide, and a polyimide film treated by rubbing can be used for thealignment films 14 a and 14 b. There is no particular limitation on thealignment films. In the present embodiment, the alignment property(alignment direction) imparted by the alignment films 14 a and 14 b tothe liquid crystal is such as to orient liquid crystal molecules inantiparallel directions between the translucent substrate 11 and thesingle crystal semiconductor substrate 12.

The spacing (cell gap) d between the translucent substrate 11 and thesingle crystal semiconductor substrate 12 is optimized by the product ofthe refractive index anisotropy Δn of an nematic liquid crystal withnegative dielectric anisotropy by the spacing d between the twosubstrates, i.e., the value of Δn·d. The substrates are bonded togetherby the resin sealing layer 15 serving as the first sealing member sothat the spacing d takes on a desired value. Thereafter, the liquidcrystal is sandwiched between the substrates to form a liquid crystalcell. The spacing d between the pair of substrates 11 and 12 can beabout 1.5 to about 5.0 μm. In the present embodiment and comparativeexamples to be described later, the spacing d is set to 3.0 μm.

For a desired cell gap to be obtained, a resin adhesive to be used forsealing is mixed with a spacer material and then the substrates eachhaving a high flatness are bonded together with the resin adhesive.Thus, a cell having the desired cell gap is formed. In the presentembodiment, a reflection type cell is manufactured using 0.7 mm-thickglass plates formed with ITO for use with a liquid crystal (1737: aproduct of Corning Incorporated), a spacer material having a spacerdiameter of 3.0 μm (SW-3.0: a product of Catalysts and ChemicalsIndustries Co., Ltd.), and an ultraviolet-thermal curable adhesive(WR-798: a product of Kyoritsu Chemical & Co., Ltd.). The cell gap ofthe reflection type cell thus manufactured is an even gap with lessnon-uniformity. After injection of the liquid crystal into the cell, theinjection hole is sealed with an ultraviolet curing resin sealingadhesive as illustrated in FIG. 2, thus forming a reflection type liquidcrystal display of the LCOS type.

A liquid crystal material used for the liquid crystal layer 17 can be acommon nematic liquid crystal with negative dielectric anisotropy. Inthe present embodiment, MLC-6608 (a product of Merck & Co., Inc.) isused as the liquid crystal material and injected into the aforementionedcell under reduced pressure, to form the reflection type liquid crystalcell. The ultraviolet curable adhesive used for end sealing is 3026B (aproduct of ThreeBond Co., Ltd.). The liquid crystal member injected iscompletely sealed with the ultraviolet curable adhesive to form thereflection type liquid crystal display of the LCOS type.

A main ingredient of the inorganic film 16 can be di-methyl-silicone oilor the like, as described above. A thin coat of such a material isapplied to an outer periphery of the resin sealing adhesive used for theperipheral sealing portion and the end-sealing portion and then formedinto the inorganic film by irradiation with an ultraviolet irradiation.The ultraviolet irradiation with which the di-methyl-silicone oil isirradiated depends on the molecular weight or the viscosity of thedi-methyl-silicone oil.

The display area can be covered with an ultraviolet shielding mask inorder to suppress damage to the liquid crystal material caused by theultraviolet radiation. The di-methyl-silicone oil can be irradiated withthe ultraviolet radiation, with the reflection type liquid crystaldisplay being heated at a temperature equal to or lower than glasstransition temperature of the resin sealing adhesive used for theperipheral sealing and the end sealing. By raising the temperature ofthe reflection type liquid crystal display, the di-methyl-silicone oilcan be irradiated with a reduced amount of energy of the ultravioletradiation.

Structural materials for use in the above-described reflection typecell, such as the substrates, liquid crystal member and resin sealingadhesive, are not particularly limited to those described in the presentdescription as long as these materials exercise like functions as thestructural materials described.

After the injection hole portion has been sealed with the ultravioletcurable adhesive cured by UV irradiation, the liquid crystal display isentirely subjected to a thermal treatment at a temperature lower than aphase transition temperature of the liquid crystal. The thermaltreatment can effectively remove moisture contained in or adsorbed tothe liquid crystal, the inside and the surface of the sealing material,and the inside and the surface of the end-sealing material. Therefore,the frequency of failures due to inclusion of moisture can be reduced inan initial state of the liquid crystal display apparatus.

A specific method of manufacturing the liquid crystal display apparatusaccording to the present invention is described below. The manufacturingprocess for the liquid crystal display apparatus according to thepresent invention includes a first step and a second step as describedbelow. A third step and a fourth step may be performed.

(1) The translucent substrate 11 and the single crystal semiconductorsubstrate 12 are bonded together with the first sealing member 15containing the spacer in such a manner that the transparent electrode 13and the reflective electrode 14 oppose each other.

(2) The liquid crystal is injected into the space defined by the pair ofsubstrates 11 and 12 and the first sealing member 15 from the injectionregion formed at the first sealing member 15 to form the liquid crystallayer 17.

(3) After the injection of the liquid crystal, the injection region issealed with the sealing member 19 to form a first structure (i.e.,liquid crystal cell) in which the liquid crystal is sandwiched betweenthe pair of substrates.

The first step includes the above-described operations (1) to (3).

(4) After the sealing with the sealing member 19, the alkylsiloxanecompound is formed by coating or a like process at an outer periphery ofthe first sealing member 15 and at an outer periphery of the sealingmember 19 in contact with the outer peripheral surfaces thereof.Alternatively, the alkylsiloxane compound is formed by coating or a likeprocess in contact with at least one of the translucent substrate 11 andthe alignment film 14 a and at least one of the single crystalsemiconductor substrate 12 and the alignment film 14 b.

(5) The alkylsiloxane compound is irradiated with the ultravioletradiation to form the second sealing member 16 including a silicon oxidefilm as an inorganic film, thus forming a second structure (i.e., liquidcrystal display).

The second step includes the above-described operations (4) and (5).

The third step of thermally treating the first structure at atemperature lower than a phase transition temperature from a liquidcrystal phase to a liquid phase of the liquid crystal, may be insertedbetween the first and second steps. Further, the fourth step ofthermally treating the second structure at a temperature lower than thephase transition temperature from the liquid crystal phase to the liquidphase of the liquid crystal, may be performed after the second step.

By thus performing the first and second steps optionally with the thirdstep and/or the fourth step, a highly moisture-resistant liquid crystaldisplay apparatus can be manufactured which is capable of suppressingdisplay deterioration due to occurrence of image retention.

A liquid crystal projector (i.e., projection type image displayapparatus) using the liquid crystal display apparatus of the presentinvention is described below. FIG. 3 is a view schematicallyillustrating one exemplary embodiment of a liquid crystal projectoraccording to the present invention.

The liquid crystal projector of the present invention has a plurality ofliquid crystal display apparatuses according to the present invention.The liquid crystal projector of the present invention is a projectiontype display including a light source for applying light to thereflection type liquid crystal displays, and a unit for displaying animage by superimposing rays of light from the plurality of reflectiontype liquid crystal displays one upon another.

The liquid crystal projector shown includes a projection lens 21 forprojecting an image onto a screen, liquid crystal displays (i.e.,reflection type liquid crystal display apparatuses) 22 a to 22 caccording to the present invention, and a polarization beam splitters 23a to 23 c each configured to allow S-polarized light to passtherethrough and reflect P-polarized light for example. The liquidcrystal projector also includes an integrator 24 configured to gatherlight from the light source, an elliptic reflector 25, an arc lamp 26using a metal halide, UHP or the like, and high-reflectance mirrors 27 aand 27 b. The liquid crystal projector further includes a G/R lightreflection dichroic mirror 28, a G light reflection dichroic mirror 29,and a color composing prism 30 configured to recompose all mono-colorlights separated by the dichroic mirrors.

The image display mechanism of the liquid crystal projector is describedbelow following the process of travel of a light beam. First, the lamp26 of the light source emits white light, which is then gathered by theelliptic reflector 25 at an entrance of the integrator 24 locatedforwardly of the reflector 25, so that a spatial intensity distributionof the light beam is uniformalized. The light beam outgoing from theintegrator 24 is reflected at a right angle by the high-reflectancemirror 27 a and reaches the G/R light reflection dichroic mirror 28.

The G/R light reflection dichroic mirror 28 reflects G/R light towardthe G light reflection dichroic mirror 29. The G light reflectiondichroic mirror 29 reflects G light, which is then polarized by passingthrough the polarization beam splitter 23 b to illuminate the reflectiontype liquid crystal display 22 b. R light passes through the G lightreflection dichroic mirror 29, travels toward the polarization beamsplitter 23 c and is then polarized by passing through the polarizationbeam splitter 23 c to illuminate the reflection type liquid crystaldisplay 22 c. On the other hand, B light passes through the G/R lightreflection dichroic mirror 28 and is then reflected at a right angle bythe high-reflectance mirror 27 b. B light thus reflected is polarized bypassing through the polarization beam splitter 23 a to illuminate thereflection type liquid crystal display 22 a.

R light, G light and B light are reflected and polarization-modulated bythe reflection type liquid crystal displays 22 a to 22 c, respectively,and then pass through the polarization beam splitters 23 a to 23 c,respectively. The light beams having passed through the polarizationbeam splitters 23 a to 23 c are turned into image light again by thecolor composing prism 30, and image light is then magnified andprojected onto the non-illustrated screen by passing through theprojection lens 21.

The moisture resistance of a reflection type liquid crystal display isevaluated by quantization of the moisture content of the reflection typeliquid crystal display having been subjected to a high-temperature andhigh-humidity environment test and conducting an image retention test.The high-temperature and high-humidity test is conducted by exposing thereflection type liquid crystal display to an environment at atemperature of 60° C. and a humidity of 90% RH for 300 hours. Themoisture content of the reflection type liquid crystal display can bedetermined by a process including heating the reflection type liquidcrystal display crashed to vaporize moisture contained therein andmeasuring the percentage of moisture content of the display using aKarl-Fischer titration apparatus. The image retention of the reflectiontype liquid crystal display is evaluated by visually checking thepresence or absence of an after image of a predetermined fixed patternwhen a uniform display is shown throughout the screen after the fixedpattern has been displayed in the display area for a fixed time period.

Exemplary Embodiments

Exemplary embodiments of the present invention are described below.

Exemplary Embodiment 1

In exemplary embodiment 1, a liquid crystal display (i.e., liquidcrystal display apparatus) was manufactured by performing the first andsecond steps of the above-described manufacturing method according tothe present invention. Initially, the first step was performed to formthe first structure (i.e., liquid crystal cell) as described above. Inthe first step, as described above, a process including forming theliquid crystal layer 17 by injecting the liquid crystal into the spacedefined by the pair of substrates 11 and 12 and the first sealing member15, was performed.

Subsequently, the second step was performed to form the second structure(i.e., liquid crystal display) as described above. Specifically,TSF-458-100 (a product of GE Toshiba Silicones Co.) was used as thedi-methyl-silicone oil serving as a main ingredient of the inorganicfilm 16. A thin coat of the di-methyl-silicone oil was applied to anouter periphery of the resin sealing adhesive used for peripheralsealing and end sealing. Thereafter, an inorganic thin film was formedby irradiation with an ultraviolet irradiation at 5,000 mJ/cm² in anordinary temperature environment, to form the second structure (i.e.,liquid crystal display). The display area was covered with anultraviolet shielding mask in order to suppress damage to the liquidcrystal material caused by the ultraviolet radiation.

Exemplary Embodiment 2

In exemplary embodiment 2, a liquid crystal display (i.e., liquidcrystal display apparatus) was manufactured by performing the first andsecond steps as in exemplary embodiment 1. Initially, in the first step,the liquid crystal was injected into the space defined by the pair ofsubstrates and the first sealing member to form the first structure, asin exemplary embodiment 1. In the second step, KF96-100cs (a product ofShin-Etsu Chemical Co., Ltd.) was used as the di-methyl-silicone oilserving as the main ingredient of the inorganic film 16, and a thin coatof the di-methyl-silicone oil was applied to an outer periphery of theresin sealing adhesive used in the peripheral sealing portion and theend-sealing portion.

Thereafter, an inorganic thin film was formed by irradiation with anultraviolet irradiation at 5,000 mJ/cm² in an ordinary temperatureenvironment, to form the second structure. The display area was coveredwith an ultraviolet shielding mask in order to suppress damage to theliquid crystal material caused by the ultraviolet radiation.

Exemplary Embodiment 3

In exemplary embodiment 3, the third step of thermally treating theabove-described first structure at a temperature lower than a phasetransition temperature from a liquid crystal phase to a liquid phase ofthe liquid crystal, was inserted between the first and second steps. Inthe present embodiment, the thermal treatment was conducted at 80° C.for 240 hours.

Before providing the second sealing member 16 of high moisturedurability, subjected to the thermal treatment are moisture andimpurities present in the liquid crystal layer 17 and at the surfaces ofthe alignment films 14 a and 14 b as well as moisture and impurities ofthe first sealing member 15. The heating treatment turns the inside ofthe liquid crystal cell into a reduced moisture and impurity condition.Thereafter, the liquid crystal display was sealed with the secondsealing member 16 having a high moisture resistance to enable the insideof the liquid crystal cell to keep the reduced moisture and impuritycondition. A liquid crystal display was manufactured by performing theabove-described first and second steps as in exemplary embodiment 1except that the third step was performed.

The reflection type liquid crystal displays manufactured in exemplaryembodiments 1 to 3 were subjected to the high-temperature andhigh-humidity environment test and then evaluated for yields thereof byprojecting an image displayed by each liquid crystal display using aliquid crystal projector. The liquid crystal projector using thereflection type liquid crystal display of exemplary embodiment 3 wasevaluated to ensure a higher yield than the liquid crystal projectorsusing the reflection type liquid crystal displays of exemplaryembodiments 1 and 2.

Exemplary embodiment 3 is particularly effective when the liquid crystalpanel assembly process has low cleanness and stability. Since thetreatment time depends on the degree of cleanness and the degree ofstability of the liquid crystal panel assembly process, in some casesthe yield is improved even when the treatment time is relatively shortand further treatment time is not necessary.

When the liquid crystal panel assembly process has low cleanness andstability, some reflection type liquid crystal displays causenon-uniformity of display picture to occur in a projected image evenjust after the manufacture thereof. However, the thermal treatmentaccording to the present embodiment can eliminate such non-uniformity ofdisplay picture while improving the yield.

Exemplary Embodiment 4

In exemplary embodiment 4, in addition to the process of exemplaryembodiment 3, the fourth step of thermally treating the above-describedsecond structure at a temperature lower than the phase transitiontemperature from the liquid crystal phase to the liquid phase of theliquid crystal, was performed after the above-described second step. Inthe present embodiment, the thermal treatment was conducted at 80° C.for 240 hours. A liquid crystal display was manufactured by performingthe process described in exemplary embodiment 3 except that the fourthstep was performed.

The reflection type liquid crystal displays manufactured in exemplaryembodiments 1, 2 and 4 were subjected to the high-temperature andhigh-humidity environment test and then evaluated for yields thereof byprojecting an image displayed by each liquid crystal display using aliquid crystal projector. The liquid crystal projector using thereflection type liquid crystal display of exemplary embodiment 4 wasevaluated to ensure a higher yield than the liquid crystal projectorsusing the reflection type liquid crystal displays of exemplaryembodiments 1 and 2.

Exemplary embodiment 4 is particularly effective when the liquid crystalpanel assembly process has low cleanness and stability. Since thetreatment time depends on the degree of cleanness and the degree ofstability of the liquid crystal panel assembly process, in some casesthe yield is improved even when the treatment time is relatively shortand further treatment time is not necessary.

When the liquid crystal panel assembly process has low cleanness andstability, some reflection type liquid crystal displays cause in-planedisplay unevenness in a projected image even just after the manufacturethereof. However, the thermal treatment according to the presentembodiment can eliminate such in-plane display unevenness whileimproving the yield.

In the present embodiment, the fourth step was performed in addition tothe process of exemplary embodiment 3. However, when the cleanness andstability of the liquid crystal panel assembly process are low, only thefourth step may be additionally performed without the third stepdescribed in exemplary embodiment 3 to bring about a satisfactoryeffect.

COMPARATIVE EXAMPLE 1

In comparative example 1, a reflection type liquid crystal display wasmanufactured in which a thin coat of TSF-458-100 (a product of GEToshiba Silicones Co.) was merely applied to an outer periphery of theresin sealing adhesive used in the peripheral sealing portion and theend-sealing portion in the liquid crystal display.

COMPARATIVE EXAMPLE 2

In comparative example 2, a reflection type liquid crystal display wasmanufactured with no treatment on the outer periphery of the peripheralsealing portion and end-sealing portion.

COMPARATIVE EXAMPLE 3

In comparative example 3, a reflection type liquid crystal display wasmanufactured in which an inorganic substance formed into aerosol wasdeposited over an outer periphery of the resin sealing adhesive used inthe peripheral sealing portion and the end-sealing portion in the liquidcrystal display. In the process of depositing and stabilizing theaerosol of the inorganic substance at the outer periphery of the resinsealing adhesive used in the peripheral sealing portion and theend-sealing portion in the liquid crystal display, sintering at 250° C.was performed.

The reflection type liquid crystal displays manufactured in exemplaryembodiments 1 to 4 and comparative examples 1 to 3 were subjected to thehigh-temperature and high-humidity environment test and then measuredfor moisture contents thereof. Also, the reflection type liquid crystaldisplays manufactured in exemplary embodiments 1 to 4 and comparativeexamples 1 to 3 were subjected to the high-temperature and high-humidityenvironment test and then evaluated for image retention by projecting animage displayed by each liquid crystal display using a liquid crystalprojector.

The moisture content determined from the percentage of moisture contentof each of the reflection type liquid crystal displays of exemplaryembodiments 1 to 4 having been subjected to the high-temperature andhigh-humidity environment test was lower than the moisture content ofany one of the reflection type liquid crystal displays of comparativeexamples 1 to 3. Thus, the reflection type liquid crystal displays ofexemplary embodiments 1 to 4 exhibited improved moisture barrierproperties. When an image was projected by a liquid crystal projectorusing each of the reflection type liquid crystal displays of exemplaryembodiments 1 to 4, the image projected by the liquid crystal projectorwas of better quality with less image retention than an image projectedby any one of liquid crystal projectors using the reflection type liquidcrystal displays of comparative examples 1 to 3.

With respect to the reflection type liquid crystal display manufacturedin comparative example 3, the cell gap and the gap evenness aredeteriorated after the sintering process at 250° C. For this reason,display unevenness is likely. Also, since the reflection type liquidcrystal display of comparative example 3 allows impurity ions toincrease, image retention is likely to occur in a short time. Therefore,the use of the reflection type liquid crystal display of comparativeexample 3 cannot provide for a liquid crystal projector of good quality.

As described above, the present invention can provide a reflection typeliquid crystal display of the LCOS type which is capable of suppressingpenetration of moisture. Therefore, the present invention can suppressdeterioration in the display properties of a liquid crystal projectorcaused by penetration of moisture into the liquid crystal display.

The above-described moisture penetration suppressing technique using theinorganic film 16 or the like is applicable to a liquid crystal displayat an ordinary temperature. For this reason, the liquid crystal displaycan be provided with a moisture penetration suppressing unit withoutdeterioration of any structural resin material. Particularly where theimage display apparatus is of the reflection type, impurities producedfrom such a structural resin material form a main cause of imageretention. The moisture penetration suppressing technique applied at anordinary temperature is particularly effective for such an arrangement.

The moisture penetration suppressing technique according to the presentinvention can be applied to a liquid crystal display in a simple andconvenient way. For this reason, a conventional liquid crystal displaymanufacturing process can be utilized with less influence upon theproductivity thereof.

By removing moisture taken in during the liquid crystal panel assemblyprocess before providing the liquid crystal display with the moisturepenetration suppressing unit, the effect of the moisture penetrationsuppressing unit becomes more noticeable. Further, the moisturepenetration suppressing technique according to the present inventiondoes not bring about any change to the outward appearance structure ofthe liquid crystal display. Therefore, the provision of the moisturepenetration suppressing unit allows little change to occur in thedimensions of the liquid crystal display. Where the image displayapparatus is of the projection type, the liquid crystal display providedwith the moisture penetration unit is a particularly advantageousarrangement in terms of layout space. The present invention isparticularly effective for such an arrangement.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2007-319706, filed Dec. 11, 2007, which is hereby incorporated byreference herein in its entirety.

1. A liquid crystal display apparatus comprising: a first sealing member arranged at an outer periphery of a liquid crystal layer sandwiched between a pair of substrates; and a second sealing member arranged at an outer periphery of the first sealing member in contact with the pair of substrates, wherein the second sealing member is formed from an alkylsiloxane compound as a main ingredient which is formed into an inorganic film by irradiation with an ultraviolet radiation.
 2. The liquid crystal display apparatus according to claim 1, wherein the alkylsiloxane compound is at a state of an alkylsiloxane structure at a temperature equal to or lower than glass transition temperature of the first sealing member.
 3. The liquid crystal display apparatus according to claim 1, wherein the alkylsiloxane compound is a di-alkylsiloxane compound, or di-methyl-siloxane compound.
 4. The liquid crystal display apparatus according to claim 1, wherein the alkylsiloxane compound is a di-methyl-silicone.
 5. The liquid crystal display apparatus according to claim 1, wherein one of the pair of substrates is a single crystalline semiconductor substrate having, inside of the first sealing member, an effective pixel region wherein a plurality of pixels each including a switching element and a reflective electrode are arranged in a two-dimensional array.
 6. The liquid crystal display apparatus according to claim 1, wherein the pair of substrates have, at opposing surfaces thereof, alignment films respectively, at least one of the alignment films of the pair of substrates is arranged in contact with the inorganic film, and the alignment film and the inorganic film are formed from the same material.
 7. The liquid crystal display apparatus according to claim 1, wherein the inorganic film is silicon oxide.
 8. A liquid crystal projector comprising: a liquid crystal display apparatus according to claim
 1. 9. A method of manufacturing a liquid crystal display apparatus comprising: a first step of injecting a liquid crystal into a space defined by a pair of substrates and a first sealing member bonding together the pair of substrates to form a first structure; and a second step of forming an alkylsiloxane compound at an outer periphery of the first sealing member in contact with the pair of substrates, and irradiating the alkylsiloxane compound with an ultraviolet radiation to form a second structure having an inorganic film.
 10. The method of manufacturing a liquid crystal display apparatus according to claim 9, further comprising: a third step of thermally treating the first structure at a temperature equal to or lower than a phase transition temperature from a liquid crystal pages to a liquid phase of the liquid crystal, after the first step before the second step.
 11. The method of manufacturing a liquid crystal display apparatus according to claim 9, further comprising: a fourth step of thermally treating the second structure at a temperature equal to or lower than a phase transition temperature from a liquid crystal pages to a liquid phase of the liquid crystal, after the second step. 